P1637: RISKS FOR A PLATELET COUNT DROP: COVID-19 &amp; ITP DATA FROM THE PLATELET DISORDER SUPPORT ASSOCIATION (PDSA) PATIENT REGISTRY
Authors: J. DiRaimo, C. Kruse, A. Kruse, M. Lambert, J. B. Bussel
Journal: HemaSphere (2022)

Background: Immune thrombocytopenia purpura (ITP) is an autoimmune bleeding disorder with low platelet counts (PC). Both vaccines and viral infections can further lower PC in ITP patients. While fear of COVID-19 influences many to receive protective vaccinations, these same vaccinations greatly concern ITP patients, since they might lower the PC. Aims: We describe data collected from the COVID-19 & ITP survey within the ITP Natural History Patient Registry on PC drops following both viral infection and vaccination to compare the effects of each on individuals with ITP. Methods: Individuals with primary or secondary ITP completed the survey. For individuals under the age of 18, the survey was completed by a legally-authorized representative (LAR). Data was collected through January 4, 2022. Results: Of 527 survey respondents, 78% were female (390); 83% were under age 65 years (418, range 5-87); and 16 (3%) were younger than 18; 170 (32%; n = 524) participants were in remission and 114 (22%; n = 524) had had previous splenectomy. Seventy participants tested positive for COVID-19. 387 reported vaccination with 282 fully vaccinated. Of 70 who were infected, 65 reported their PC change with A PC drop in 21 (32%). Recovery to baseline was within 3 months in 91% and within 1 month in 67%. Among 387 who reported receiving vaccine dose 1 (D1), 119 (31%) reported a PC drop. Recovery to baseline was within 3 months (77%) and 1 month (57%). Among the 282 who received dose 2 (D2), 87 (31%) had a PC drop. Recovery to baseline was within 3 months (83%) and 1 month (62%). Of 119 participants with a PC drop after (D1), 68 (57%) received D2. Of these 68, 45 (66%) reported a PC drop after both D1+D2, more than the entire group (282) who received D2 (X2 = 29.1, p = 0.00001). PC drops were not necessarily greater with subsequent doses. Among 45 participants who experienced PC drops following D1+D2, PC drops were larger with: a) D1 in 13 (28%) b) D2 in 7 (16%), and c) the same following D1 and D2 in 25 (56%). Of 45 participants reporting a PC drop post D1+D2, most were females (34; 76%) between 22-64 years (33; 73%), similar to the overall survey demographics. Eight (18%) participants with a PC drop following D1+D2 had had a previous splenectomy (same as the 22% overall). Summary/Conclusion: One-third of participants experienced a PC drop following either viral infection or vaccine receipt which further supports the safety of COVID-19 vaccination in patients with ITP. For the 31% of patients that had a PC drop following D1, there was an increased probability of a PC drop with D2, however for more than half of those patients the degree of PC drop was not greater with D2. Age, gender, and splenectomy status did not influence the risk for PC drops with either the D1 or D2. PC changes following both infection and vaccination were short-lived and generally recovered within 1 month. These findings should further reduce vaccine hesitancy among ITP patients.